A known example of a display device is a liquid crystal display device in in-plane switching (IPS) mode. The liquid crystal display device in IPS mode comprises a pair of substrates facing each other via a liquid crystal layer. One of the substrates comprises a pixel electrode and a common electrode. The alignment of the liquid crystal molecules of the liquid crystal layer is controlled using the lateral electric field generated between the electrodes. A liquid crystal display device in fringe-field switching (FFS) mode has been put to practical use. In the liquid crystal display device in FFS mode, a pixel electrode and a common electrode are provided in different layers, and the fringe electric field generated between the electrodes is used to control the alignment of liquid crystal molecules.
A liquid crystal display device, in which a pixel electrode and a common electrode are provided in different layers, a slit is provided in the electrode closer to a liquid crystal layer than the other electrode, and the liquid crystal molecules near the both sides of the slit in the width direction are rotated in opposite directions, has been developed. The system of this liquid crystal display device is clearly different from the FFS mode, and can increase the speed of response and improve the stability of alignment in comparison with the conventional FFS mode. Hereinafter, the structure of this type of liquid crystal display device is called a high-speed response mode.
In the liquid crystal display device in high-speed response mode, an electric field which does not contribute to the above alignment control may be generated between the pixel electrode and the common electrode. When such an electric field has acted on the liquid crystal layer, the alignment is changed in an undesired way, and thus, the display quality is degraded.